<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<script src="./vue.js"></script>

<body>
  <div id="app">
    <p>{{msg | toUpcase}}</p>
  </div>
  <script>
    const vm = new Vue({
      el: "#app",
      data: {
        msg: "li wen tao "
      },
      filters: {
        toUpcase(values) {
          return values ? values.toUpperCase() : "";
        }
      },
    });
  </script>
</body>

</html>